On Sun, Jan 31, 2010 at 10:14:03PM +1100, Anton Blanchard wrote:
> > With dynamic irq descriptors the overhead of a large NR_IRQS is much lower> than it used to be. With more MSI-X capable adapters and drivers exploiting > multiple vectors we may as well allow the user to increase it beyond the> current maximum of 512.> > 32768 seems large enough that we'd never have to bump it again (although I bet> my prediction is horribly wrong). It boot tests OK and the vmlinux footprint> increase is only around 500kB due to:
Only 1/2 MB?
I'm running Linux on 12 year old PPC machines which have 16MB
or RAM (ok, they are still running an old kernel, but a few
patches like this and they wont't even boot). The kernels
I have are well below 1MB, code+data+bss.
Yes it is configurable, thanks, and 64 is enough for these
machines (8259 plus an MPIC), so it's not that crucial.
What I object to is calling 1/2MB negligible.
Gabriel

On Mon, 2010-02-01 at 10:09 +0100, Gabriel Paubert wrote:
> On Sun, Jan 31, 2010 at 10:14:03PM +1100, Anton Blanchard wrote:> > > > With dynamic irq descriptors the overhead of a large NR_IRQS is much lower> > than it used to be. With more MSI-X capable adapters and drivers exploiting > > multiple vectors we may as well allow the user to increase it beyond the> > current maximum of 512.> > > > 32768 seems large enough that we'd never have to bump it again (although I bet> > my prediction is horribly wrong). It boot tests OK and the vmlinux footprint> > increase is only around 500kB due to:> > Only 1/2 MB? > > I'm running Linux on 12 year old PPC machines which have 16MB> or RAM (ok, they are still running an old kernel, but a few> patches like this and they wont't even boot). The kernels> I have are well below 1MB, code+data+bss. > > Yes it is configurable, thanks, and 64 is enough for these> machines (8259 plus an MPIC), so it's not that crucial.> > What I object to is calling 1/2MB negligible.
Yeah well, all Anton did was to push up the -max- value you can set in
the config, not the default :-)
But yeah, it's not "negligible" per-se.
Cheers,
Ben.